The Runner - Peter May

A top Chinese swimmer kills himself on the eve of an international event, shattering his country's hopes of victory against the Americans. An Olympic weightlifter dies in the arms of his Beijing mistress, a scandal to be hushed up at the highest level. These two deaths could be a tragic coincidence—or something more sinister.
When Beijing detective Li Yan discovers that these are not the first of China's athletes to die, he brings American pathologist Margaret Campbell out of retirement to find out if natural causes may be concealing very unnatural deaths.
The key to the case lies with a champion runner, the only member of the athletics team prepared to talk. But when the runner disappears, time starts to run out for Li Yan to catch the killer.